With advances in technology, mobile communication systems include wireless data packet communication systems of high speed and high quality. Such communication systems provide data service and multimedia service, beyond the initial voice-oriented services. The development of High Speed Downlink Packet Access (HSDPA), which progressed as part of the 3rd Generation Partnership Project (3GPP), can be viewed as a representative effort for providing a wireless data packet transport service having high quality at over 2 Mbps in the 3G mobile communication system.
In a 3GPP long term evolution (3GPP LTE) system, when a transport block is large, the transport block is segmented into multiple codeblocks so that multiple coded packets can be generated, which is advantageous because of benefits such as enabling parallel processing or data pipelining and to facilitate flexibility with respect to trade-offs between power consumption and hardware complexity.
In a contemporary High Speed Data Shared Channel (HS-DSCH) design, only one 24-bit cyclic redundancy check (CRC) is generated for the whole transport block for the purpose of error detection for that block. If multiple codeblocks are generated and transmitted in one transmission time interval (TTI), the receiver may correctly decode some of the codeblocks but not the others. In that case, the receiver will generate a non-acknowledgement (NAK) feedback message to the transmitter because the CRC for the transport block did not pass the check.